Influence of Surface-Chemical Modification on the Optical Properties of TiO₂ Semiconductor Ultrafine Particles

Optical properties of TiO₂ semiconductor ultrafine particles （UFPs） with surface—chemical modification were studied by measuring absorption, photoluminescence and excitation spectra as well as the decay times of luminescence in this paper. The influence of quantum size effect, interfacial dipole effect and dielectric confinement effect on the optical properties of TiO₂ UFPs is discussed. It is found that the absorption band edges of TiO₂ UFPs coated with a layer of surfactant molecules in organosols significantly shift to the red and clear photoluminescence is observed at room temperature, which are in contrast with that of bulk TiO₂.